U.S. patent application number 11/571525 was filed with the patent office on 2008-08-28 for motor-driven vehicle with transmission.
This patent application is currently assigned to VOLVO LASTVAGNAR AB. Invention is credited to Magnus Blanckenfjell, Anders Eriksson, Anders Lindgren, Marcus Steen.
Application Number | 20080208418 11/571525 |
Document ID | / |
Family ID | 32768757 |
Filed Date | 2008-08-28 |
United States Patent
Application |
20080208418 |
Kind Code |
A1 |
Eriksson; Anders ; et
al. |
August 28, 2008 |
Motor-Driven Vehicle with Transmission
Abstract
A motor-driven vehicle includes at least an engine, control
devices arranged to control a transmission driven by the engine, a
first sensor that is arranged to communicate with the control
devices, and a second sensor that is arranged to communicate with
the control devices, with the control devices being arranged to
receive a first signal sent from the first sensor that includes
information about the gradient of the surface on which the vehicle
is being driven, and with the control devices being arranged to
receive a second signal sent from the second sensor that includes
information about torque. The control devices are arranged to
correct the first signal in response to the second signal, and to
control the transmission in response to the corrected first signal,
and thereby compensate for the effect of the torque on the first
sensor.
Inventors: |
Eriksson; Anders; (Goteborg,
SE) ; Steen; Marcus; (Angered, SE) ;
Blanckenfjell; Magnus; (Goteborg, SE) ; Lindgren;
Anders; (Goteborg, SE) |
Correspondence
Address: |
WRB-IP LLP
1217 KING STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
VOLVO LASTVAGNAR AB
Goteborg
SE
|
Family ID: |
32768757 |
Appl. No.: |
11/571525 |
Filed: |
June 28, 2005 |
PCT Filed: |
June 28, 2005 |
PCT NO: |
PCT/SE2005/001035 |
371 Date: |
December 18, 2007 |
Current U.S.
Class: |
701/51 |
Current CPC
Class: |
F16H 61/0213 20130101;
Y10T 477/33 20150115; Y10T 477/6333 20150115; F16H 59/18 20130101;
F16H 59/66 20130101; F16H 2059/147 20130101; F16H 59/24 20130101;
F16H 2059/663 20130101 |
Class at
Publication: |
701/51 |
International
Class: |
G06F 7/00 20060101
G06F007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 2, 2004 |
SE |
0401742-2 |
Claims
1. A motor-driven vehicle comprising an engine, control devices
arranged to control a transmission driven by the engine, a first
sensor that is arranged to communicate with the control devices,
and a second sensor that is arranged to communicate with the
control devices, wherein the control devices are arranged to
receive a first signal sent from the first sensor that comprises
information about a gradient of a surface on which the vehicle is
being driven, and wherein the control devices being are arranged to
receive a second signal sent from the second sensor that comprises
information about torque, wherein the control devices are arranged
to correct the first signal in response to the second signal, and
to control the transmission in response to the corrected first
signal, and thereby compensate for an effect of the torque on the
first sensor.
2. The motor-driven vehicle as claimed in claim 1, wherein the
second sensor is a torque sensor that is arranged to measure torque
of an incoming shaft to the transmission and/or the torque of an
outgoing shaft from the transmission and/or the vehicle's engine
torque.
3. The motor-driven vehicle as claimed in claim 1, wherein the
first sensor is a sensor that is arranged to measure throttle
position, throttle position corresponding to information about a
quantity of fuel supplied to the engine.
4. The motor-driven vehicle as claimed in claim 1, wherein the
correction is carried out in response to a predetermined correction
function.
5. The motor-driven vehicle as claimed in claim 4, wherein there is
at least one correction function for each gear in the
transmission.
6. A method for detection of resistance to travel for a
motor-driven vehicle, with the method comprising the steps of:
receiving a first signal comprising information about a gradient of
a surface on which the vehicle is being driven, the first signal
being sent from a gradient sensor; receiving a second signal
comprising information about torque; correcting the first signal in
response to the second signal; and controlling a transmission in
response to the corrected first signal to compensate for an effect
of the torque on the gradient sensor.
7. The method as claimed in claim 6, comprising correcting the
first signal in response to the second signal comprising
information about at least one of torque of an incoming shaft to
the vehicle's transmission, the torque of an outgoing shaft from
the vehicle's transmission, and the vehicle's engine torque.
8. The method as claimed in claim 6, comprising correcting the
first signal in response to the second signal comprising
information about a quantity of fuel supplied to the engine.
9. A computer program product comprising program code for carrying
out the method steps in claim 6, when the computer program is
executed by a computer.
10. A computer program product comprising program code stored on a
medium that can be read by a computer for carrying out the method
steps in claim 6, when the computer program is executed by the
computer.
Description
[0001] The present invention relates to a motor vehicle comprising
an engine and control devices that are arranged to control a
transmission that is driven by the engine.
[0002] The invention also relates to a method for detection of the
motor-driven vehicle's resistance to travel.
[0003] The invention also relates to a computer program for
carrying out the said method.
[0004] In vehicles with automatic or semi-automatic gearboxes, it
is important to use as accurate an estimation as possible of the
vehicle's resistance to travel in order to be able to provide
optimal gear changing regimes according to certain given criteria,
such as, for example, low fuel consumption or high average
speed.
[0005] EP0512596 describes a method for the control of gear
selection in which changing up and down is modified in response to
a detected road resistance. A resistance higher than normal can be
caused by a trailer, steep gradients or unusual air dynamics. A
load equation balances the torque of the outgoing shaft from the
transmission against the resistance to travel and provides
continually an indication of whether the resistance to travel is
higher than normal. EP0512596 describes how the resistance in
excess of the normal is used to modify a basic gear change regime
in order to provide earlier changing down and later changing up.
When the resistance in excess of the normal exceeds a particular,
relatively high, value, then changing up is further delayed in
order to counteract the detected resistance.
[0006] It is desirable to provide a motor vehicle in which a better
estimation of the vehicle's resistance to travel is obtained.
[0007] It is desirable to obtain in a cost-effective way a better
estimation of the gradient of the surface on which the- vehicle is
being driven.
[0008] According to an aspect of the present invention, a
motor-driven vehicle comprises at least an engine, control devices
arranged to control a transmission driven by the engine, a first
sensor that is arranged to communicate with the control devices,
and a second sensor that is arranged to communicate with the
control devices, with the control devices being arranged to receive
a first signal sent from the first sensor that comprises
information about the gradient of the surface on which the vehicle
is being driven, and with the control devices being arranged to
receive a second signal sent from the second sensor that comprises
information about torque, with the invention being characterized in
that the control devices are also arranged to correct the first
signal in response to the second signal, and to control the
transmission in response to the corrected first signal, and thereby
compensate for the effect of the torque on the first sensor.
[0009] The vehicle performs better while being driven, as control
of the transmission is based on more correct information. The
vehicle can thus, for example, be driven in a more fuel-economic
way.
[0010] The said correction is preferably carried out in response to
a predetermined correction function. In this way, there is an
improvement in the accuracy of information that is used as the
basis for making decisions for control of the transmission. There
is preferably at least one correction function for each gear in the
transmission. This has the advantage that there is a further
improvement in the accuracy of information that is used as the
basis for making decisions for control of the transmission.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 shows a schematic illustration of a motor-driven
vehicle and a control system for the same.
[0012] FIG. 2 shows a cable with examples of detected or calculated
data, which is used according to the invention.
[0013] FIG. 3a shows schematically a side view of a motor vehicle
that is on a surface.
[0014] FIG. 3b shows two coordinate systems that are used according
to an embodiment of the invention.
[0015] FIG. 3c shows an outline drawing of how the gradient of the
surface on which the vehicle is being driven is defined according
to an embodiment of the invention.
[0016] FIG. 3d shows a table of measured and calculated data that
is used according to an embodiment of the invention.
[0017] FIG. 3e illustrates a graph of measured and calculated data
that is used according to an embodiment of the invention.
[0018] FIG. 3f shows an outline drawing of how the gradient of the
surface on which the vehicle is being driven is defined according
to an embodiment of the invention.
[0019] FIG. 4a shows a flow chart illustrating a method according
to an embodiment of the invention. FIG. 4b shows a flow chart
illustrating a method for storage of information according" to an
embodiment of the invention.
[0020] FIG. 4c shows a flow chart illustrating a method for storage
of information according to an embodiment of the invention.
[0021] FIG. 4d shows a flow chart illustrating a curve fitting
method according to an embodiment of the invention.
[0022] FIG. 4e shows a flow chart illustrating a method for
compensating for the measured gradient according to an embodiment
of the invention.
[0023] FIG. 4f shows a flow chart illustrating a curve fitting
updating method according to an embodiment of the invention.
[0024] FIG. 5 shows schematically a computer device that is used
according to an embodiment of the invention.
DETAILED DESCRIPTION
[0025] FIG. 1 shows a schematic illustration of a vehicle 1 and a
control system for the same according to an embodiment of the
present invention in which 10 represents a combustion engine, for
example a six-cylinder diesel engine, the crankshaft 20 of which is
connected to a single-disk dry disk clutch represented in general
by 30, which is enclosed in a clutch case 40. Instead of a
single-disk clutch, a double-disk clutch can be used. The
crankshaft 20 is connected to the clutch case 50 of the clutch 30
in such a way that it cannot rotate, while its disk 60 is connected
to an incoming shaft 70 in such a way that it cannot rotate, which
shaft is mounted in the housing 80 of a gearbox represented in
general by 90 in such a way that it can rotate. A main shaft and an
intermediate shaft are mounted in the housing 80 in such a way that
they can rotate. An outgoing shaft 85 from the gearbox 90 is
arranged to drive the vehicle's wheels.
[0026] In addition, a first control unit 48 for control of the
engine 10 and a second control unit 45 for control of the
transmission 90 are illustrated. The first and second control units
are arranged to communicate with each other via a cable 21. It is
described in the following that different processes and method
steps are carried out in the second control unit 45, but it should
be made clear that the invention is not restricted to this, in that
the first control unit 48 can similarly be used, or a combination
of the first and second control units. The second control unit 45
is arranged to communicate with the transmission 90 via a cable 24.
The first control unit 48 is arranged to communicate with the
engine 10 via a cable 26. The first and second control units can,
in general, be designated as control devices.
[0027] The vehicle 1 has a throttle 44 and a manual gear selector
46, which are arranged to communicate with the second control unit
45 via a cable 210 and 211 respectively. The gear selector 46 can
have a position for manual change of gear and a position for
automatic change of gear in the vehicle. The throttle can be an
accelerator pedal. A sensor 113 is arranged to measure continually
the position of the throttle. The sensor 113 is arranged to
communicate with the second control unit 45 and hence also with the
first control unit 48. The position of the throttle indicates
implicitly the quantity of fuel that is supplied to the engine's
combustion chamber. The quantity of fuel supplied indicates the
engine torque. The second control unit 45 can thus continually
calculate a value representing the engine torque on the basis of
the signal sent from the sensor 113.
[0028] Detectors 111 are arranged to detect, measure, estimate or
record different states of, among other things, the engine 10. The
detectors can be of different kinds. Examples of detectors are
engine torque sensors 111a, acceleration sensors 111b and engine
output sensors 111c. In FIG. 1, detectors are only shown in general
represented by 111. The detectors 111 are arranged to communicate
with the first control unit 48 by means of a cable 28.
[0029] According to an embodiment, a torque sensor 110 is arranged
to measure the torque of the incoming shaft 70. The torque sensor
110 is arranged to measure the torque that is achieved by the
engine 10 on the incoming shaft 70. The torque sensor 110 is
arranged to communicate with the second control unit 45 via a cable
22. The torque sensor 110 is arranged to communicate continually to
the second control unit 45 a momentary value representing the
torque of the incoming shaft. The communicated value representing
the torque of the incoming shaft can be communicated to the second
control unit in the form of an electrical signal. The signal can
alternatively be an optical signal. The signal can be analog or
digital. The second control unit is arranged to convert the
received signal in a suitable way, for example by means of an A/D
transducer (not shown in the figure).
[0030] In an alternative embodiment, the torque sensor 110 is
arranged to measure the torque of the outgoing shaft 85. The torque
sensor 110 is arranged to measure the torque that is achieved by
the engine 10 on the outgoing shaft 85. It should be apparent that
the torque sensor that is arranged in this way is arranged to
measure torque within a wider range than in the case of measuring
the torque of the incoming shaft.
[0031] In a preferred embodiment, the torque sensor 110 is located
on the incoming shaft as, in this case, it can easily be used for
other applications, such as, for example, clutch control. The data
received from the torque sensor is recorded in the second control
unit 45. The received data which is recorded by the second control
unit 45 is stored in a memory in the second control unit. According
to an embodiment, data measured by the torque sensor and then
stored in the memory in the second control unit 45 relates to
torque with associated time stamps. According to an embodiment,
momentary torque values T(i) are measured each 100th millisecond
(0.1 s) and each estimated value is stored with an associated time
stamp R(i). The time stamps R(i) are generated by the second
control unit 45, where i is an integer between 1 and N. N is an
integer, for example 1000. Table 1 below shows an example of four
initial measurements for the transmission's first and lowest gear
during throttling of the vehicle, for example during acceleration
or engine braking. Corresponding measurements can be carried out
for all of the transmission's gears and can be stored in tables in
the second control unit 45.
TABLE-US-00001 TABLE 1 Measured torque T(i) with respective time
stamps R(i). (i) T(i) [Nm] R(i) [s] 1 0 0.100 2 100 0.200 3 200
0.300 4 300 0.400
[0032] As the transmission's gear and efficiency are known, the
torque of the outgoing shaft 85 of the engine can be continually
calculated. As the torque of the outgoing shaft is different for
different selected gears, this is taken into account in the
calculations. Any additional units that are present are also taken
into account, in order to obtain good estimations of the torque.
According to an embodiment, data representing calculated values for
the torque of the outgoing shaft 85 is stored together with
associated time stamps in the memory in the second control unit
45.
[0033] According to an embodiment, the engine's torque is
calculated on the basis of the quantity of fuel injected into the
engine's combustion chamber. The calculation can be carried out in
the second control unit. According to this embodiment, this
calculated value representing the engine's torque can be used
according to the invention.
[0034] A gradient sensor 115 is already arranged in association
with the gearbox 90. According to a preferred embodiment, the
gradient sensor is already arranged in the gearbox 90. The gradient
sensor 115 is arranged to measure the gradient of the surface on
which the vehicle 1 is located, in particular while it is in
motion. The surface can be a road, the gradient of which is
measured. The gradient sensor 115 can be of piezo-electrical type.
The gradient sensor 115 is arranged to communicate with the second
control unit 45 via a cable 23. According to a preferred
embodiment, the gradient sensor is arranged to send signals
representing the gradient of the surface continually to the second
control unit.
[0035] According to another embodiment, signals representing the
gradient of the surface are sent to the second control unit at
certain intervals, for example at intervals of 0.01 seconds or 0.5
seconds.
[0036] According to an embodiment, signals representing the
gradient of the surface are sent continually from the gradient
sensor 115 to the second control unit 45 and are stored there in an
array together with respective time stamps, according to the above.
The array is stored in the second control unit 45. The array is
also referred to as a table.
[0037] According to an embodiment, values SM(i) representing the
gradient of the surface are measured by means of the gradient
sensor 115 each 100th millisecond (0.1 s) and each measured value
is stored with a respective corresponding time stamp R(i). The time
stamps R(i) are generated by the second control unit 45, where i is
an integer. Table 2 below shows an example of four initial
measurements for the transmission's first and lowest gear.
Corresponding measurements can be carried out for all of the
transmission's gears and can be stored in files in the second
control unit. Note that the time stamps are the same as described
above, with reference to Table 1. Thus, SM(T) and T(T) are measured
essentially simultaneously, that is they are a first data pair
(i=1) measured after 0.1 seconds (R(T)). SM(2) and T(2) are
measured essentially simultaneously, that is they are a second data
pair (i=2) measured after 0.2 seconds (R(2)). In Table 2, the
respective measured gradients are not stated explicitly.
TABLE-US-00002 TABLE 2 Measured gradient of the surface on which
the vehicle is being driven SM(i) with respective time stamps R(i).
(i) SM(i) (x, y, z) [%] R(i) [s] 1 SM(1) 0.1 2 SM(2) 0.2 3 SM(3)
0.3 4 SM(4) 0.4
[0038] FIG. 2 shows the cable 28 and examples of motion data
detected, measured, estimated or recorded by the detectors 111.
Examples of motion data are, for example, engine torque 201,
crankshaft torque 202, engine output 203, vehicle's acceleration
204, exhaust gas back pressure 205 and fuel consumption 206.
[0039] In addition, detectors 111d (not shown in the figure) are
arranged to measure bellows pressure for the vehicle's different
wheels.
[0040] FIG. 3a illustrates schematically a side view of the motor
vehicle 1 comprising, among other things, the engine 1, the control
units 45 and 48, the torque sensor 110 and the gradient sensor 115
and other parts shown in FIG. 1.
[0041] Two orthogonal coordinate systems are introduced, namely a
first orthogonal coordinate system C1(X, Y, Z) and a second
orthogonal coordinate system C2(X, Y, Z). The two coordinate
systems C1 and C2 are introduced as tools for describing movements
in the vehicle's chassis relative to the surface on which the
vehicle is being driven caused by a torque in the vehicle's drive
line.
[0042] The first coordinate system C1(X, Y, Z) has its origin O1 at
a specified point located in or outside the vehicle. The second
coordinate system C2(X, Y, Z) has its origin 02 in the gradient
sensor 115 and is displaced relative to the first coordinate
system. The size and direction of the displacement are described by
a vector P from O1 to 02. The displacement of the second coordinate
system relative to the first coordinate system can be zero (0),
that is, there can be no displacement at all. The first coordinate
system C1(X, Y, Z) and the second coordinate system C2(X, Y, Z) are
described in greater detail below.
[0043] FIG. 3b illustrates in greater detail the first coordinate
system C1(X, Y, Z) and the second coordinate system C2(X, Y,
Z).
[0044] The first coordinate system C1(X, Y, Z) has its origin 01 at
a specified" point in or outside the vehicle 1. When the motor
vehicle is stationary on a flat surface, the X1-axis in the
vehicle's direction of travel is parallel with the flat surface.
The Y1-axis is orthogonal to the X1-axis (and thus also
perpendicular to the flat surface), in an upward direction from the
surface. The Z1-axis is orthogonal to both the X1-axis and the
Y1-axis and thus points in a direction out from a side of the
vehicle. In the figure, the Z1-axis goes in a direction out from
the right side of the vehicle, viewed in the direction of travel of
the vehicle. The position of the specified point (01) does not
change significantly when the vehicle is in motion. It should be
apparent that C1 accordingly represents a coordinate system that is
always oriented in the way described above for the case when the
motor vehicle is stationary on a flat surface.
[0045] The surface's momentary gradient is represented by the
vector P1 in the first coordinate system C1(X, Y, Z). The first
coordinate system has a reference vector P1ref(X.sub.1, Y.sub.1,
Z.sub.1)=P1(0, 1, 0). The reference vector P1ref(X.sub.1, Y.sub.1,
Z.sub.1)=P1(0, 1, 0) thus indicates the normal to the surface when
the vehicle is stationary on a flat surface. Both P1ref and P1 are
unit vectors and have accordingly the length 1.
[0046] In ideal conditions, the gradient sensor 115 can measure the
gradient of the surface with a relatively high degree of accuracy.
Ideal conditions can mean that the vehicle is stationary or is
being driven at a constant speed on a horizontal surface. Other
ideal conditions can be that the vehicle is freewheeling on an
upward or downward incline with a constant gradient. Yet another
ideal condition can be when the vehicle is being driven on a
varying surface with an interruption in the drive continuity, for
example a change of gear. What is common to these conditions is
that the gradient sensor is essentially stabilized and can
therefore provide a value that is a good representation of the
gradient of the surface.
[0047] P1 is thus an ideal value (direction) of the gradient sensor
that essentially correctly represents the gradient of the surface.
On a flat horizontal surface in ideal conditions P1ref and P1 thus
coincide.
[0048] On a downward incline, however, P1 will follow the surface
and indicate the normal to the surface, as shown in FIG. 3b. Assume
that the surface is a flat road that has a downward gradient of 5
degrees. The road gradient is represented by a. In FIG. 3b in this
case P1=P1(X.sub.1, Y.sub.1, Z.sub.1)=P1(sin(.alpha.),
cos(.alpha.), 0).
[0049] In an alternative embodiment, the direction of P1 is
represented by two solid angles .beta..sub.1 and .gamma..sub.1.
.beta..sub.1 represents the angle
(0.ltoreq..beta..sub.1.ltoreq..pi.) in the X1-Y1 plane .beta..sub.1
coincides with X1. .gamma..sub.1 represents the angle
(0.ltoreq..gamma..sub.1.ltoreq..pi.) in the Y1-Z1 plane where
.gamma..sub.1=O coincides with Z1. .beta..sub.1 and .gamma..sub.1
are not shown in the figure.
[0050] The second coordinate system C2(X, Y, Z) has its origin 02
located in the centre of the gradient sensor. The respective axes
of C1(X, Y, Z) and C2(X, Y, Z) are parallel. This means, for
example, that X1 and X2 are parallel. C2 has a vector that starts
from 02. P2 is a unit vector and has accordingly the length 1. P2
represents the value that the gradient sensor actually measures,
that is, the value that the gradient sensor measures as the
gradient of the surface, but that is actually a combination of the
gradient of the surface and a twisting in the chassis (and
accordingly also a movement of the gradient sensor) that is caused
by the torque in the vehicle's drive line.
[0051] P2 is thus an incorrect value (direction) representing the
surface on which the vehicle is being driven that the gradient
sensor 115 measures and sends to the second control unit 48 as a
basis for further calculations, such as, for example, a basis for a
gear selection strategy. The signal is incorrect in as much as it
does not represent a completely correct value representing the
gradient of the surface.
[0052] In an embodiment, the direction of P2 is represented by two
solid angles .beta..sub.2 and .gamma..sub.2. .beta..sub.2
represents an angle (0.ltoreq..beta..sub.2.ltoreq..pi.) in the
X2-Y2 plane where .beta..sub.2=0 coincides with X2. .gamma..sub.2
represents the angle (0.ltoreq..gamma..sub.2.ltoreq..pi.) in the
Y2-Z2 plane where Y2=O coincides with Z2. .beta..sub.2 and
.gamma..sub.2 are not shown in the figure.
[0053] A vector P3 starts from P1 and points to P2, as shown in the
figure.
[0054] In the case when O1 and 02 coincide, P3 indicates the
relative difference between P1 and P2. This relative difference can
be due to a movement of the vehicle's chassis relative to the
surface on which the vehicle is being driven that is caused by the
torque in the vehicle's drive line.
[0055] According to an aspect of the invention, it is recorded how
the measured gradient (P2) depends upon the torque of the incoming
shaft 70. By utilizing information about how the measured gradient
varies as a function of the torque of the incoming shaft 70, a
better estimation of the actual gradient of the surface can be
obtained. According to an embodiment of the invention, P2 is
measured, after which P3 is added to P2 to obtain P1 which is a
better estimation of the surface on which the vehicle is being
driven. If required, there is also compensation for the
displacement between the two coordinate systems C1 and C2
represented by P.
[0056] Thus, P1=P2+P3
[0057] P3 is obtained by utilizing a curve fitting of a graph that
shows how the measured gradient (P2) depends upon the torque T of
the incoming shaft 70.
[0058] In FIG. 3c, a broken line B illustrates a cross section of a
horizontal plane. A solid line A illustrates a cross section of a
flat surface that has a gradient radians relative to the horizontal
plane B. The solid line A can typically represent a cross section
of a flat road on which the vehicle 1 is being driven. The line C,
that consists of alternating long and short lines, represents an
(incorrect) gradient of the surface B measured by the gradient
sensor when the vehicle is being driven on the surface. The
measured gradient differs from the actual gradient by azradians.
The measured gradient of the surface has a gradient Of 3radians
relative to the horizontal plane B.
[0059] Thus, .alpha.1+.alpha.2=.alpha.3
[0060] Of course, there is the possibility that the measured
gradient of the surface is less than the actual gradient, as
illustrated in FIG. 3f.
[0061] Thus, in this case, .alpha.1-.alpha.2=.alpha.3
[0062] FIG. 3d illustrates a table of measured and calculated
values according to an embodiment of the invention. In cases when
the torque of, for example, the incoming shaft changes rapidly,
that is changes a relatively large amount in a short time, the
gradient of the surface can be assumed to be constant. In these
cases, associated values are recorded from the gradient sensor,
that is measured gradient SM(i) and nominal gradient SN(i), and
from the torque sensor, that is T(i), as described above. The
difference in gradient value D(i) is calculated for the respective
associated values and is stored in the table together with the
associated torque T(i). D(i) is thus calculated on the basis of
SM(i) and SN(i).
[0063] In the simplest case, in the event of a change of gear, the
torque is reduced to zero (0) and a value representing the
difference in gradient can be obtained for a particular torque,
that is the torque from which the reduction took place. For
example, a deviation between a value SM(i) for the gradient of the
surface measured by the gradient sensor 115 and an actual value
SN(i) for the same can be 0.7% (in one plane, as shown for example
with reference to FIG. 3c) for a torque T(i) corresponding to 1000
Nm.
[0064] According to an embodiment of the present invention, in
cases where the torque is not zero (0), for example in the event of
a sudden torque increase, a previously stored value for the one
torque value (SM(i)) can be used as a reference instead of zero
(0). In this way, other tables, with different reference values,
can be created. These can then be used to create functions that
describe the deviation F(T) as described below.
[0065] N rows can be stored in the table. N is an integer. N can,
for example, be 500.
[0066] The table shown in FIG. 3d comprises measured and calculated
values for a first gear G1. According to an embodiment of the
invention, there are corresponding tables for all the vehicle's
gears. Thus, according to an embodiment, where the transmission has
12 different gears, there is a table for each of the transmission's
12 gears. Storage of data in the different tables is carried out as
described above. The different tables are designated G1 to G12 for
the respective gears.
[0067] FIG. 3e illustrates a graph F(T). F(T) is a function that
describes how the deviation between the measured gradient of the
surface on which the vehicle is being driven and the actual
gradient of the surface on which the vehicle is being driven
depends on a torque T, for example the torque of the incoming shaft
70. Data D(I), T(I), D(2), T(2), . . . , D(7), T(7) is given in the
table G1 illustrated with reference to FIG. 3d. According to this
embodiment, the graph is obtained by curve fitting to measured
data. According to an embodiment, curve fitting can be carried out
by the method of least squares, which gives the linear dependency
that is shown in FIG. 3e. Here F(T)=kT+m, where k and m are
constants. Curve fitting can, however, be carried out in different
ways. For example, curve fitting can be carried out with different
polynomials. The fitted curve is thus not limited to being a
straight line.
[0068] According to an embodiment of the invention, a function F(T)
is created for each of the tables G1-G12 and is designated
F1(T)-F12(T).
[0069] FIG. 4a shows a flow chart illustrating a method for
detection of resistance to travel for a motor-driven vehicle
according to an embodiment of the invention. According to a first
method step s401, the subsidiary steps are carried out of:
[0070] receiving a first signal comprising information about the
gradient of the surface on which the vehicle is being driven, sent
from a gradient sensor;
[0071] receiving a second signal comprising information about
torque;
where the method is characterized by the subsidiary steps the steps
of [0072] correcting the first signal in response to the second
signal; and of [0073] controlling the vehicle's transmission in
response to the corrected first signal, and thereby compensating
for the effect of the torque on the gradient sensor.
[0074] According to an embodiment of the method, the first signal
is corrected in response to the second signal comprising
information about the torque of an incoming shaft to the vehicle's
transmission.
[0075] According to an embodiment of the method, the first signal
is corrected in response to the second signal comprising
information about the torque of an outgoing shaft from the
vehicle's transmission.
[0076] According to an embodiment of the method, the first signal
is corrected in response to the second signal comprising
information about the vehicle's engine torque.
[0077] According to an embodiment of the method, the first signal
is corrected in response to a value representing a quantity of fuel
supplied to the engine's combustion chamber.
[0078] FIG. 4b shows a flow chart illustrating a method for storing
data according to an embodiment of the invention. In a first method
step s404, it is detected which gear the vehicle's transmission
system is in.
[0079] In a subsequent method step s406, it is determined whether a
table already exists for the detected gear. If such is the case,
that is "Yes", a method step s450 follows with reference to FIG.
4c. If there is not already a created table, that is "No", a method
step s408 follows.
[0080] In method step 408, a table is created for storage of
measured data, such as detected torque T(i) and gradient SM(i) and
SN(i). The table is intended to store measured or processed data
relating to a specific gear in the vehicle's drive line, that is
the gear that is detected in the method step s404. The detected
gear can be the gearbox's lowest gear, also called a first gear.
According to this example, a created table is the one that is shown
with reference to FIG. 3d, that is G1. The table is created and is
stored in a memory in the second control unit 45. The table is
empty after it has been created. The table is dynamic, that is more
rows can be created as more measured data is stored. Rows in the
table can be created automatically by the second control unit as
received data is recorded.
[0081] In a method step s412, a value for measured torque T(i) is
recorded. According to an embodiment, the recorded value T(i) is a
value representing torque upon the initiation of a change of gear.
After the method step s412, the method step s416 follows.
[0082] In the method step s416, a value SM(i) and corresponding
SN(i) are recorded. According to a preferred embodiment, the
received value SM(i) is represented by the vector j?2. The method
step s416 is followed by a method step s418.
[0083] In the method step s418, the deviation D(i) is calculated
that gives the difference in gradient between the measured gradient
SM(i) and the nominal gradient SN(i). Depending upon how the
gradients SM(i) and SN(i) are represented, this can be carried out
in different ways. One way is to indicate the difference in
gradient D(i) in one plane (the X-Y plane) expressed by an angle
.alpha.2radians, as shown in FIG. 3c. The method step s418 is
followed by a method step s420.
[0084] In the method step s420, T(i), SN(i), SM(i) and D(i) are
stored in a memory in the second control unit 45, if required also
with corresponding time stamp R(i) (not shown in FIG. 3d). The
method step s420 is followed by a method step s424.
[0085] In the method step s424, a decision is reached whether one
of the above procedures is to be repeated, that is whether a new
row containing new T(i), SN(i), SM(i) and D(i) for a subsequent
time (i+1) is to be inserted in the table. If such is the case,
that is "Yes", the method step s412 follows. If such is not the
case, that is "No", the method is terminated. A program stored in
the second control unit 45 controls the decision making in
accordance with certain criteria. FIG. 4c shows a flow chart
illustrating a method for storage of data in a table according to
an embodiment of the invention.
[0086] In the method step s450, a decision is reached concerning
which table (for example) G1-12 is to be selected for storage of
data T(i), SN(i), SM(i) and D(i) with a particular time stamp.
According to a preferred embodiment, the table is selected on the
basis of which gear the said data has been detected and calculated
for.
[0087] In a method step s453, a measured value T(i) is recorded.
After the method step s453, the method step s456 follows.
[0088] In the method step s456, gradient values SM(i) and SN(i) are
recorded, in accordance with s416. After the method step s456, the
method step s457 follows.
[0089] In the method step s457, the deviation D(i) is calculated,
in accordance with s418. After the method step s457, the method
step s459 follows.
[0090] In the method step s459, T(i), SN(i), SM(i) and D(i) are
stored in a memory in the second control unit 45, in accordance
with s420. The method step s459 is followed by a method step
s462.
[0091] In the method step s462, a decision is reached whether one
of the above procedures is to be repeated, in accordance with s424.
If such is the case, that is "Yes", the method step s450 follows.
If such is not the case, that is "No", the method is
terminated.
[0092] FIG. 4d shows a flow chart illustrating a method for curve
fitting according to an embodiment of the invention. In a method
step s480, a decision is reached concerning which table is to be
selected for generation of a curve fitting (for example, any one of
the previously mentioned G1-G12). The decision can be based on the
fact that a particular criterion is fulfilled. A criterion can be
that the table contains a particular number of rows with data T(i),
SN(i), SM(i) and D(i). The method step s480 is followed by a method
step s483.
[0093] In the method step s483, the data is selected that is
relevant for the curve fitting. According to a preferred
embodiment, all torque values T(i) and corresponding deviations
D(i) are retrieved. In another embodiment of the invention, certain
data (T(i) and corresponding deviations D(i)) is selected. In this
way, some values can be excluded from the curve fitting procedure.
The method step s483 is followed by a method step s485.
[0094] In method step s485, a graph is created based on the data
selected in method step s483. According to an embodiment, the graph
is a function F(T) described above. The method step s485 is
followed by a method step s488.
[0095] In the method step s488, the graph (or the function F(T))
created in method step s485 is stored in a memory in the second
control unit 45. After the method step s488, the method is
terminated.
[0096] FIG. 4e shows a flow chart illustrating a method for
compensating for measured gradients according to an embodiment of
the invention.
[0097] In a method step s470, a momentary torque Tm(i) is recorded,
for example the torque of the incoming shaft. This momentary torque
causes the gradient sensor 115 to measure a value representing the
gradient of the surface SMm(i) with a certain deviation F(Tm(i)).
Tm(i) and SMm(i) have the same time stamp R(i). According to an
embodiment, this momentary torque Tm(i) causes the gradient sensor
115 to measure a value representing the gradient of the surface P2
with a certain deviation P3 from the more correct value P1.
According to an embodiment, this momentary torque Tm causes the
gradient sensor 115 to measure a value representing the gradient of
the surface U3 with a certain deviation .alpha..sub.2 from the more
correct value .alpha..sub.1. The method step s470 is followed by a
method step s472.
[0098] In a method step s472, SMm(i) is recorded.
[0099] In the method step s473, it is selected which curve (or
function F(T)) is to be used to calculate a correction for the
momentary recorded gradient SMm. The curve is selected on the basis
of which gear is selected. The method step s473 is followed by a
method step s475.
[0100] In the method step s475, a correction is calculated for the
measured gradient SMm(i) for the corresponding measured torque
Tm(i) using the selected function F(T). This calculated correction
is used later by the second control unit to control the changing of
gear in the vehicle's transmission. Thus, the measured momentary
signal SMm(i) is corrected according to the above in order to be
used in calculations for controlling the changing of gear in the
vehicle's transmission.
[0101] After the method step s475, the method is terminated.
[0102] FIG. 4f shows a flow chart illustrating a method for
updating one of the functions F1(T) to F12(T) according to an
embodiment of the invention.
[0103] In a method step s490, a decision is reached concerning
which table's G1-12 corresponding function F1(T)-F12(T) is to be
updated. In this case, G1 is selected and thus F1(T) is to be
updated. The method step s490 is followed by a method step
s492.
[0104] In method step s492, a new graph F1(T) is created in
accordance with s485, with new stored data T(i), SN(i), SM(i) and
D(i) also being comprised in the curve fitting.
[0105] In the method step s498, the old function F1(T) is updated
to the new function F1(T) and becomes the valid function until the
next update takes place. The method step s498 is followed by a
method step s499.
[0106] In the method step s499, the updated function F1(T) is
stored in a memory in the second control unit 45. After method step
s499, the method is terminated.
[0107] FIG. 5 shows an apparatus 500, according to an aspect of the
invention, comprising a non-volatile memory 520, a processor 510
and a read and write memory 560. The memory 520 has a first memory
module 530, in which a computer program for controlling the
apparatus 500 is stored. The computer program in the memory module
530 for controlling the apparatus 500 can be an operating
system.
[0108] The apparatus 500 can be contained in, for example, a
control unit, such as the control unit 45 or 48. According to a
preferred embodiment, an apparatus 500 is incorporated in both the
first and second control unit 45 and 48 respectively. The
data-processing unit 510 can comprise, for example, a
microcomputer.
[0109] The memory 520 has also a second memory module 540, in which
a program is stored comprising methods with reference to the FIGS.
4a-4f. In an alternative embodiment, the program is stored on a
separate nonvolatile data-storage medium 550, such as, for example,
a CD-ROM or a replaceable semiconductor memory. The program can be
stored in an executable form or in a compressed state.
[0110] When it is described in the following that the
data-processing unit 510 runs a special function, it should be
clear that the data-processing unit 510 runs a special part of the
program which is stored in the memory 540 or a special part of the
program which is stored on the non-volatile recording medium
550.
[0111] The data-processing unit 510 is arranged to communicate with
the memory 550 by means of a data bus 514. The data-processing unit
510 is also arranged to communicate with the memory 520 by means of
a data bus 512. In addition, the data-processing unit 510 is
arranged to communicate with the memory 560 by means of a data bus
511. The data-processing unit 510 is also arranged to communicate
with a data port 590 by means of a data bus 515.
[0112] The methods that are described in FIGS. 4a-f can be carried
out by the data-processing unit 510 by means of the data-processing
unit 510 running the program which is stored in the memory 540 or
the program which is stored on the non-volatile recording medium
550.
[0113] In the second memory module 540, a computer program is
stored comprising program code for carrying out method steps
according to the flow charts, with reference to any one of the
FIGS. 4a-f, when the said computer program is executed by a
computer.
[0114] For utilization of the invention, there is a computer
program product comprising program code stored on a medium that can
be read by a computer for carrying out method steps according to
the flow charts, with reference to any one of the FIGS. 4a-f, when
the said computer program is executed by the computer. For
utilization of the invention, there is a computer program product
that can be loaded directly into an internal memory in a computer,
comprising a computer program for carrying out method steps
according to the flow charts, with reference to any one of the
FIGS. 4a-f, when the said computer program product is executed by
the computer.
* * * * *